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• Protecting IP for scripting projects

  - by Francisco Garcia

  There are some tasks where the obvious language choice is with scripting languages: bash, Python, Ruby, Tcl... however I find it hard to protect a company IP once the product is delivered because the application is never compiled. The client will have complete access to every single line of code. Which one are the choices to protect a product IP when it is best implemented with scripting languages? (switching to a compiled language such as C++ should not be an option) I know that some interpreted languages can be compiled, but there are cases where the process can be inverted

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• Is "programmatically" a word? [closed]

  - by Lo'oris

  I can't find it on any of the online dictionaries I know: dict.org, word reference, urban dictionary, oxford paravia, garzanti. To my ears of a non-native speaker, it sounds horrible. Actually it sounds like a word made-up by another non-native speaker that wanted to say something, didn't know how, and just hacked in a word of his language. The only place I've read it other then user-created-content is the android documentation, so this might or might not be related. Do you happen to know where did it start to be used, why by did it spread so much, what does it really mean?

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• Will Haskell be a good choice for my task?

  - by Narzanka

  I'm starting a new project and don't know which language to use. My 'must have' requirements are: Be able to run on Windows/LinuxMacOs natively (native executable) - user should be able to just run the exe (when on Windows for example) and see the results. No runtimes/interpreters (no jvm, clr, etc) - one file download should be enough to run the application. Full unicode support. Be able to manipulate OS threads (create them, run multiple tasks in parallel on multi-core CPUs, etc). Be reasonably fast (Python level performance and better). To have some kind of standard library that does low-level, mundane tasks. Not very niche and have some community behind it to be able to ask questions. My 'nice to have' requirements are: Language should be functional It should have good string manipulation capabilities (not necessarily regex) Not extremely hard to learn I'm thinking about Haskell now but keeping in mind OCaml as well. Please advice if my choice is correct.

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• Desired features for C++

  - by bytepusher

  I am a full time C++ developer, and I really like the language. I think it is suited for almost any kind of application. Some people claim Java and C# are better suited for high level programming, but I'm not so sure about this. I have worked with all three languages, and when using C++, it happens only now and then I come across something that might be improved. What features would you like to see added to C++? I'm talking about big improvements, not details like typesafe enums.

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• Private vs. Public members in practice (how important is encapsulation?)

  - by Asmor

  One of the biggest advantages of object-oriented programming is encapsulation, and one of the "truths" we've (or, at least, I've) been taught is that members should always be made private and made available via accessor and mutator methods, thus ensuring the ability to verify and validate the changes. I'm curious, though, how important this really is in practice. In particular, if you've got a more complicated member (such as a collection), it can be very tempting to just make it public rather than make a bunch of methods to get the collection's keys, add/remove items from the collection, etc. Do you follow the rule in general? Does your answer change depending on whether it's code written for yourself vs. to be used by others? Are there more subtle reasons I'm missing for this obfuscation?

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• So my girlfriend wants to learn to program [closed]

  - by vanstee

  Possible Duplicate: What programming language should be taught in Computer Science 101? My girlfriend hates feeling completely out of the loop when my friends and I talk about anything related to computers, so she asked me to teach her how to program. I'm pretty happy she asked, but I want to be able to teach her enough to know the basics without her completely losing interest or getting too frustrated. She is a very smart girl, probably smarter than me, but her computer related skills are pretty minimal. What language should I teach her and why?

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• How to optimize dynamic programming?

  - by Chan

  Problem A number is called lucky if the sum of its digits, as well as the sum of the squares of its digits is a prime number. How many numbers between A and B are lucky? Input: The first line contains the number of test cases T. Each of the next T lines contains two integers, A and B. Output: Output T lines, one for each case containing the required answer for the corresponding case. Constraints: 1 <= T <= 10000 1 <= A <= B <= 10^18 Sample Input: 2 1 20 120 130 Sample Output: 4 1 Explanation: For the first case, the lucky numbers are 11, 12, 14, 16. For the second case, the only lucky number is 120. The problem is quite simple if we use brute force, however the running time is so critical that my program failed most test cases. My current idea is to use dynamic programming by storing the previous sum in a temporary array, so for example: sum_digits(10) = 1 -> sum_digits(11) = sum_digits(10) + 1 The same idea is applied for sum square but with counter equals to odd numbers. Unfortunately, it still failed 9 of 10 test cases which makes me think there must be a better way to solve it. Any idea would be greatly appreciated. #include <iostream> #include <vector> #include <string> #include <algorithm> #include <unordered_map> #include <unordered_set> #include <cmath> #include <cassert> #include <bitset> using namespace std; bool prime_table[1540] = { 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0 }; unsigned num_digits(long long i) { return i > 0 ? (long) log10 ((double) i) + 1 : 1; } void get_sum_and_sum_square_digits(long long n, int& sum, int& sum_square) { sum = 0; sum_square = 0; int digit; while (n) { digit = n % 10; sum += digit; sum_square += digit * digit; n /= 10; } } void init_digits(long long n, long long previous_sum[], const int size = 18) { int current_no_digits = num_digits(n); int digit; for (int i = 0; i < current_no_digits; ++i) { digit = n % 10; previous_sum[i] = digit; n /= 10; } for (int i = current_no_digits; i <= size; ++i) { previous_sum[i] = 0; } } void display_previous(long long previous[]) { for (int i = 0; i < 18; ++i) { cout << previous[i] << ","; } } int count_lucky_number(long long A, long long B) { long long n = A; long long end = B; int sum = 0; int sum_square = 0; int lucky_counter = 0; get_sum_and_sum_square_digits(n, sum, sum_square); long long sum_counter = sum; long long sum_square_counter = sum_square; if (prime_table[sum_counter] && prime_table[sum_square_counter]) { lucky_counter++; } long long previous_sum[19] = {1}; init_digits(n, previous_sum); while (n < end) { n++; if (n % 100000000000000000 == 0) { previous_sum[17]++; sum_counter = previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[16] = 0; previous_sum[15] = 0; previous_sum[14] = 0; previous_sum[13] = 0; previous_sum[12] = 0; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10000000000000000 == 0) { previous_sum[16]++; sum_counter = previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[15] = 0; previous_sum[14] = 0; previous_sum[13] = 0; previous_sum[12] = 0; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 1000000000000000 == 0) { previous_sum[15]++; sum_counter = previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[14] = 0; previous_sum[13] = 0; previous_sum[12] = 0; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 100000000000000 == 0) { previous_sum[14]++; sum_counter = previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[13] = 0; previous_sum[12] = 0; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10000000000000 == 0) { previous_sum[13]++; sum_counter = previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[12] = 0; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 1000000000000 == 0) { previous_sum[12]++; sum_counter = previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[11] = 0; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 100000000000 == 0) { previous_sum[11]++; sum_counter = previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[10] = 0; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10000000000 == 0) { previous_sum[10]++; sum_counter = previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[9] = 0; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 1000000000 == 0) { previous_sum[9]++; sum_counter = previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[8] = 0; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 100000000 == 0) { previous_sum[8]++; sum_counter = previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[7] = 0; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10000000 == 0) { previous_sum[7]++; sum_counter = previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[6] = 0; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 1000000 == 0) { previous_sum[6]++; sum_counter = previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[5] = 0; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 100000 == 0) { previous_sum[5]++; sum_counter = previous_sum[5] + previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[5] * previous_sum[5] + previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[4] = 0; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10000 == 0) { previous_sum[4]++; sum_counter = previous_sum[4] + previous_sum[5] + previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[4] * previous_sum[4] + previous_sum[5] * previous_sum[5] + previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[3] = 0; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 1000 == 0) { previous_sum[3]++; sum_counter = previous_sum[3] + previous_sum[4] + previous_sum[5] + previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[3] * previous_sum[3] + previous_sum[4] * previous_sum[4] + previous_sum[5] * previous_sum[5] + previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[2] = 0; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 100 == 0) { previous_sum[2]++; sum_counter = previous_sum[2] + previous_sum[3] + previous_sum[4] + previous_sum[5] + previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[2] * previous_sum[2] + previous_sum[3] * previous_sum[3] + previous_sum[4] * previous_sum[4] + previous_sum[5] * previous_sum[5] + previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[1] = 0; previous_sum[0] = 0; } else if (n % 10 == 0) { previous_sum[1]++; sum_counter = previous_sum[1] + previous_sum[2] + previous_sum[3] + previous_sum[4] + previous_sum[5] + previous_sum[6] + previous_sum[7] + previous_sum[8] + previous_sum[9] + previous_sum[10] + previous_sum[11] + previous_sum[12] + previous_sum[13] + previous_sum[14] + previous_sum[15] + previous_sum[16] + previous_sum[17] + previous_sum[18]; sum_square_counter = previous_sum[1] * previous_sum[1] + previous_sum[2] * previous_sum[2] + previous_sum[3] * previous_sum[3] + previous_sum[4] * previous_sum[4] + previous_sum[5] * previous_sum[5] + previous_sum[6] * previous_sum[6] + previous_sum[7] * previous_sum[7] + previous_sum[8] * previous_sum[8] + previous_sum[9] * previous_sum[9] + previous_sum[10] * previous_sum[10] + previous_sum[11] * previous_sum[11] + previous_sum[12] * previous_sum[12] + previous_sum[13] * previous_sum[13] + previous_sum[14] * previous_sum[14] + previous_sum[15] * previous_sum[15] + previous_sum[16] * previous_sum[16] + previous_sum[17] * previous_sum[17] + previous_sum[18] * previous_sum[18]; previous_sum[0] = 0; } else { sum_counter++; sum_square_counter += ((n - 1) % 10) * 2 + 1; } // get_sum_and_sum_square_digits(n, sum, sum_square); // assert(sum == sum_counter && sum_square == sum_square_counter); if (prime_table[sum_counter] && prime_table[sum_square_counter]) { lucky_counter++; } } return lucky_counter; } void inout_lucky_numbers() { int n; cin >> n; long long a; long long b; while (n--) { cin >> a >> b; cout << count_lucky_number(a, b) << endl; } } int main() { inout_lucky_numbers(); return 0; }

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• Google AJAX Transliteration API :- How do i translate many elements in page to some language at one

  - by Nitesh Panchal

  Hello, I have many elements on page and all of which i want to translate to some language. The language is not the same for all fields, that is, for 1st field it may be fr and for third field it may be en then again for 7th field it may be pa. Basically i wrote the code and it's working :- <script type="text/javascript"> //<![CDATA[ google.load("language", "1"); window.onload = function(){ var elemPostTitles = document.getElementsByTagName("h4"); var flag = true; for(var i = 0 ; i < elemPostTitles.length ; i++){ while(flag == false){ } var postTitleElem = elemPostTitles[i]; var postContentElem = document.getElementById("postContent_" + i); var postTitle = postTitleElem.innerHTML; var postContent = postContentElem.innerHTML; var languageCode = document.getElementById("languageCode_" + i).value; google.language.detect(postTitle, function(result) { if (!result.error && result.language) { google.language.translate(postTitle, result.language, languageCode, function(result) { flag = true; if (result.translation) { postTitleElem.innerHTML = result.translation; } }); } }); flag = false; } As you can see, what i am trying to do is restrict the loop from traversing until the result of previous ajax call is receieved. If i don't do this only the last field gets translated. My code works nicely, but because of the infinite loop, i keep getting errors from Mozilla to "stop executing scripts". How do i get rid of this? Also, is my approach correct? Or some inbuilt function is available which can ease my task? Thanks in advance :)

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• Which programming idiom to choose for this open source library?

  - by Walkman

  I have an interesting question about which programming idiom is easier to use for beginner developers writing concrete file parsing classes. I'm developing an open source library, which one of the main functionality is to parse plain text files and get structured information from them. All of the files contains the same kind of information, but can be in different formats like XML, plain text (each of them is structured differently), etc. There are a common set of information pieces which is the same in all (e.g. player names, table names, some id numbers) There are formats which are very similar to each other, so it's possible to define a common Base class for them to facilitate concrete format parser implementations. So I can clearly define base classes like SplittablePlainTextFormat, XMLFormat, SeparateSummaryFormat, etc. Each of them hints the kind of structure they aim to parse. All of the concrete classes should have the same information pieces, no matter what. To be useful at all, this library needs to define at least 30-40 of these parsers. A couple of them are more important than others (obviously the more popular formats). Now my question is, which is the best programming idiom to choose to facilitate the development of these concrete classes? Let me explain: I think imperative programming is easy to follow even for beginners, because the flow is fixed, the statements just come one after another. Right now, I have this: class SplittableBaseFormat: def parse(self): "Parses the body of the hand history, but first parse header if not yet parsed." if not self.header_parsed: self.parse_header() self._parse_table() self._parse_players() self._parse_button() self._parse_hero() self._parse_preflop() self._parse_street('flop') self._parse_street('turn') self._parse_street('river') self._parse_showdown() self._parse_pot() self._parse_board() self._parse_winners() self._parse_extra() self.parsed = True So the concrete parser need to define these methods in order in any way they want. Easy to follow, but takes longer to implement each individual concrete parser. So what about declarative? In this case Base classes (like SplittableFormat and XMLFormat) would do the heavy lifting based on regex and line/node number declarations in the concrete class, and concrete classes have no code at all, just line numbers and regexes, maybe other kind of rules. Like this: class SplittableFormat: def parse_table(): "Parses TABLE_REGEX and get information" # set attributes here def parse_players(): "parses PLAYER_REGEX and get information" # set attributes here class SpecificFormat1(SplittableFormat): TABLE_REGEX = re.compile('^(?P<table_name>.*) other info \d* etc') TABLE_LINE = 1 PLAYER_REGEX = re.compile('^Player \d: (?P<player_name>.*) has (.*) in chips.') PLAYER_LINE = 16 class SpecificFormat2(SplittableFormat): TABLE_REGEX = re.compile(r'^Tournament #(\d*) (?P<table_name>.*) other info2 \d* etc') TABLE_LINE = 2 PLAYER_REGEX = re.compile(r'^Seat \d: (?P<player_name>.*) has a stack of (\d*)') PLAYER_LINE = 14 So if I want to make it possible for non-developers to write these classes the way to go seems to be the declarative way, however, I'm almost certain I can't eliminate the declarations of regexes, which clearly needs (senior :D) programmers, so should I care about this at all? Do you think it matters to choose one over another or doesn't matter at all? Maybe if somebody wants to work on this project, they will, if not, no matter which idiom I choose. Can I "convert" non-programmers to help developing these? What are your observations? Other considerations: Imperative will allow any kind of work; there is a simple flow, which they can follow but inside that, they can do whatever they want. It would be harder to force a common interface with imperative because of this arbitrary implementations. Declarative will be much more rigid, which is a bad thing, because formats might change over time without any notice. Declarative will be harder for me to develop and takes longer time. Imperative is already ready to release. I hope a nice discussion will happen in this thread about programming idioms regarding which to use when, which is better for open source projects with different scenarios, which is better for wide range of developer skills. TL; DR: Parsing different file formats (plain text, XML) They contains same kind of information Target audience: non-developers, beginners Regex probably cannot be avoided 30-40 concrete parser classes needed Facilitate coding these concrete classes Which idiom is better?

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• "Translator by Moth"

  - by Daniel Moth

  This article serves as the manual for the free Windows Phone 7 app called "Translator by Moth". The app is available from the following link (browse the link on your Window Phone 7 phone, or from your PC with zune software installed): http://social.zune.net/redirect?type=phoneApp&id=bcd09f8e-8211-e011-9264-00237de2db9e   Startup At startup the app makes a connection to the bing Microsoft Translator service to retrieve the available languages, and also which languages offer playback support (two network calls total). It populates with the results the two list pickers ("from" and "to") on the "current" page. If for whatever reason the network call fails, you are informed via a message box, and the app keeps trying to make a connection every few seconds. When it eventually succeeds, the language pickers on the "current" page get updated. Until it succeeds, the language pickers remain blank and hence no new translations are possible. As you can guess, if the Microsoft Translation service add more languages for textual translation (or enables more for playback) the app will automatically pick those up. "current" page The "current" page is the main page of the app with language pickers, translation boxes and the application bar. Language list pickers The "current" page allows you to pick the "from" and "to" languages, which are populated at start time. Until these language get populated with the results of the network calls, they remain empty and disabled. When enabled, tapping on either of them brings up on a full screen popup the list of languages to pick from, formatted as English Name followed by Native Name (when the latter is known). The "to" list, in addition to the language names, indicates which languages have playback support via a * in front of the language name. When making a selection for the "to" language, and if there is text entered for translation, a translation is performed (so there is no need to tap on the "translate" application bar button). Note that both language choices are remembered between different launches of the application.   text for translation The textbox where you enter the translation is always enabled. When there is nothing entered in it, it displays (centered and in italics) text prompting you to enter some text for translation. When you tap on it, the prompt text disappears and it becomes truly empty, waiting for input via the keyboard that automatically pops up. The text you type is left aligned and not in italic font. The keyboard shows suggestions of text as you type. The keyboard can be dismissed either by tapping somewhere else on the screen, or via tapping on the Windows Phone hardware "back" button, or via taping on the "enter" key. In the latter case (tapping on the "enter" key), if there was text entered and if the "from" language is not blank, a translation is performed (so there is no need to tap on the "translate" application bar button). The last text entered is remembered between application launches. translated text The translated text appears below the "to" language (left aligned in normal font). Until a translation is performed, there is a message in that space informing you of what to expect (translation appearing there). When the "current" page is cleared via the "clear" application bar button, the translated text reverts back to the message. Note a subtle point: when a translation has been performed and subsequently you change the "from" language or the text for translation, the translated text remains in place but is now in italic font (attempting to indicate that it may be out of date). In any case, this text is not remembered between application launches. application bar buttons and menus There are 4 application bar buttons and 4 application bar menus. "translate" button takes the text for translation and translates it to the translated text, via a single network call to the bing Microsoft Translator service. If the network call fails, the user is informed via a message box. The button is disabled when there is no "from" language available or when there is not text for translation entered. "play" button takes the translated text and plays it out loud in a native speaker's voice (of the "to" language), via a single network call to the bing Microsoft Translator service. If the network call fails, the user is informed via a message box. The button is disabled when there is no "to" language available or when there is no translated text available. "clear" button clears any user text entered in the text for translation box and any translation present in the translated text box. If both of those are already empty, the button is disabled. It also stops any playback if there is one in flight. "save" button saves the entire translation ("from" language, "to" language, text for translation, and translated text) to the bottom of the "saved" page (described later), and simultaneously switches to the "saved" page. The button is disabled if there is no translation or the translation is not up to date (i.e. one of the elements have been changed). "swap to and from languages" menu swaps around the "from" and "to" languages. It also takes the translated text and inserts it in the text for translation area. The translated text area becomes blank. The menu is disabled when there is no "from" and "to" language info. "send translation via sms" menu takes the translated text and creates an SMS message containing it. The menu is disabled when there is no translation present. "send translation via email" menu takes the translated text and creates an email message containing it (after you choose which email account you want to use). The menu is disabled when there is no translation present. "about" menu shows the "about" page described later. "saved" page The "saved" page is initially empty. You can add translations to it by translating text on the "current" page and then tapping the application bar "save" button. Once a translation appears in the list, you can read it all offline (both the "from" and "to" text). Thus, you can create your own phrasebook list, which is remembered between application launches (it is stored on your device). To listen to the translation, simply tap on it – this is only available for languages that support playback, as indicated by the * in front of them. The sound is retrieved via a single network call to the bing Microsoft Translator service (if it fails an appropriate message is displayed in a message box). Tap and hold on a saved translation to bring up a context menu with 4 items: "move to top" menu moves the selected item to the top of the saved list (and scrolls there so it is still in view) "copy to current" menu takes the "from" and "to" information (language and text), and populates the "current" page with it (switching at the same time to the current page). This allows you to make tweaks to the translation (text or languages) and potentially save it back as a new item. Note that the action makes a copy of the translation, so you are not actually editing the existing saved translation (which remains intact). "delete" menu deletes the selected translation. "delete all" menu deletes all saved translations from the "saved" page – there is no way to get that info back other than re-entering it, so be cautious. Note: Once playback of a translation has been retrieved via a network call, Windows Phone 7 caches the results. What this means is that as long as you play a saved translation once, it is likely that it will be available to you for some time, even when there is no network connection.   "about" page The "about" page provides some textual information (that you can view in the screenshot) including a link to the creator's blog (that you can follow on your Windows Phone 7 device). Use that link to discover the email for any feedback. Other UI design info As you can see in the screenshots above, "Translator by Moth" has been designed from scratch for Windows Phone 7, using the nice pivot control and application bar. It also supports both portrait and landscape orientations, and looks equally good in both the light and the dark theme. Other than the default black and white colors, it uses the user's chosen accent color (which is blue in the screenshot examples above). Feedback and support Please report (via the email on the blog) any bugs you encounter or opportunities for performance improvements and they will be fixed in the next update. Suggestions for new features will be considered, but given that the app is FREE, no promises are made. If you like the app, don't forget to rate "Translator by Moth" on the marketplace. Comments about this post welcome at the original blog.

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• Code Golf: Collatz Conjecture

  - by Earlz

  Inspired by http://xkcd.com/710/ here is a code golf for it. The Challenge Given a positive integer greater than 0, print out the hailstone sequence for that number. The Hailstone Sequence See Wikipedia for more detail.. If the number is even, divide it by two. If the number is odd, triple it and add one. Repeat this with the number produced until it reaches 1. (if it continues after 1, it will go in an infinite loop of 1 -> 4 -> 2 -> 1...) Sometimes code is the best way to explain, so here is some from Wikipedia function collatz(n) show n if n > 1 if n is odd call collatz(3n + 1) else call collatz(n / 2) This code works, but I am adding on an extra challenge. The program must not be vulnerable to stack overflows. So it must either use iteration or tail recursion. Also, bonus points for if it can calculate big numbers and the language does not already have it implemented. (or if you reimplement big number support using fixed-length integers) Test case Number: 21 Results: 21 -> 64 -> 32 -> 16 -> 8 -> 4 -> 2 -> 1 Number: 3 Results: 3 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1 Also, the code golf must include full user input and output.

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• Is it a good practice to suppress warnings?

  - by Chris Cooper

  Sometimes while writing Java in Eclipse, I write code that generates warnings. A common one is this, which I get when extending the Exception class: public class NumberDivideException extends Exception { public NumberDivideException() { super("Illegal complex number operation!"); } public NumberDivideException(String s) { super(s); } } // end NumberDivideException The warning: The serializable class NumberDivideException does not declare a static final serialVersionUID field of type long. I know this warning is caused by my failure to... well, it says right above. I could solve it by including the serialVersionUID, but this is a one hour tiny assignment for school; I don't plan on serializing it anytime soon... The other option, of course, is to let Eclipse add @SuppressWarnings("serial"). But every time my mouse hovers over the Suppress option, I feel a little guilty. For programming in general, is it a good habit to suppress warnings? (Also, as a side question, is adding a "generated" serialVersionUID like serialVersionUID = -1049317663306637382L; the proper way to add a serialVersionUID, or do I have to determine the number some other way?)

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• Scalable / Parallel Large Graph Analysis Library?

  - by Joel Hoff

  I am looking for good recommendations for scalable and/or parallel large graph analysis libraries in various languages. The problems I am working on involve significant computational analysis of graphs/networks with 1-100 million nodes and 10 million to 1+ billion edges. The largest SMP computer I am using has 256 GB memory, but I also have access to an HPC cluster with 1000 cores, 2 TB aggregate memory, and MPI for communication. I am primarily looking for scalable, high-performance graph libraries that could be used in either single or multi-threaded scenarios, but parallel analysis libraries based on MPI or a similar protocol for communication and/or distributed memory are also of interest for high-end problems. Target programming languages include C++, C, Java, and Python. My research to-date has come up with the following possible solutions for these languages: C++ -- The most viable solutions appear to be the Boost Graph Library and Parallel Boost Graph Library. I have looked briefly at MTGL, but it is currently slanted more toward massively multithreaded hardware architectures like the Cray XMT. C - igraph and SNAP (Small-world Network Analysis and Partitioning); latter uses OpenMP for parallelism on SMP systems. Java - I have found no parallel libraries here yet, but JGraphT and perhaps JUNG are leading contenders in the non-parallel space. Python - igraph and NetworkX look like the most solid options, though neither is parallel. There used to be Python bindings for BGL, but these are now unsupported; last release in 2005 looks stale now. Other topics here on SO that I've looked at have discussed graph libraries in C++, Java, Python, and other languages. However, none of these topics focused significantly on scalability. Does anyone have recommendations they can offer based on experience with any of the above or other library packages when applied to large graph analysis problems? Performance, scalability, and code stability/maturity are my primary concerns. Most of the specialized algorithms will be developed by my team with the exception of any graph-oriented parallel communication or distributed memory frameworks (where the graph state is distributed across a cluster).

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• What's with the love of dynamic Languages

  - by Kibbee

  It seems that everybody is jumping on the dynamic, non-compiled bandwagon lately. I've mostly only worked in compiled, static typed languages (C, Java, .Net). The experience I have with dynamic languages is stuff like ASP (Vb Script), JavaScript, and PHP. Using these technologies has left a bad taste in my mouth when thinking about dynamic languages. Things that usually would have been caught by the compiler such as misspelled variable names and assigning an value of the wrong type to a variable don't occur until runtime. And even then, you may not notice an error, as it just creates a new variable, and assigns some default value. I've also never seen intellisense work well in a dynamic language, since, well, variables don't have any explicit type. What I want to know is, what people find so appealing about dynamic languages? What are the main advantages in terms of things that dynamic languages allow you to do that can't be done, or are difficult to do in compiled languages. It seems to me that we decided a long time ago, that things like uncompiled asp pages throwing runtime exceptions was a bad idea. Why is there is a resurgence of this type of code? And why does it seem to me at least, that Ruby on Rails doesn't really look like anything you couldn't have done with ASP 10 years ago?

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• Heuristic to identify if a series of 4 bytes chunks of data are integers or floats

  - by flint

  What's the best heuristic I can use to identify whether a chunk of X 4-bytes are integers or floats? A human can do this easily, but I wanted to do it programmatically. I realize that since every combination of bits will result in a valid integer and (almost?) all of them will also result in a valid float, there is no way to know for sure. But I still would like to identify the most likely candidate (which will virtually always be correct; or at least, a human can do it). For example, let's take a series of 4-bytes raw data and print them as integers first and then as floats: 1 1.4013e-45 10 1.4013e-44 44 6.16571e-44 5000 7.00649e-42 1024 1.43493e-42 0 0 0 0 -5 -nan 11 1.54143e-44 Obviously they will be integers. Now, another example: 1065353216 1 1084227584 5 1085276160 5.5 1068149391 1.33333 1083179008 4.5 1120403456 100 0 0 -1110651699 -0.1 1195593728 50000 These will obviously be floats. PS: I'm using C++ but you can answer in any language, pseudo code or just in english.

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• Code Golf: Quickly Build List of Keywords from Text, Including # of Instances

  - by Jonathan Sampson

  I've already worked out this solution for myself with PHP, but I'm curious how it could be done differently - better even. The two languages I'm primarily interested in are PHP and Javascript, but I'd be interested in seeing how quickly this could be done in any other major language today as well (mostly C#, Java, etc). Return only words with an occurrence greater than X Return only words with a length greater than Y Ignore common terms like "and, is, the, etc" Feel free to strip punctuation prior to processing (ie. "John's" becomes "John") Return results in a collection/array Extra Credit Keep Quoted Statements together, (ie. "They were 'too good to be true' apparently")Where 'too good to be true' would be the actual statement Extra-Extra Credit Can your script determine words that should be kept together based upon their frequency of being found together? This being done without knowing the words beforehand. Example: "The fruit fly is a great thing when it comes to medical research. Much study has been done on the fruit fly in the past, and has lead to many breakthroughs. In the future, the fruit fly will continue to be studied, but our methods may change." Clearly the word here is "fruit fly," which is easy for us to find. Can your search'n'scrape script determine this too? Source text: http://sampsonresume.com/labs/c.txt Answer Format It would be great to see the results of your code, output, in addition to how long the operation lasted.

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• Code Golf: Easter Spiral

  - by friol

  What's more appropriate than a Spiral for Easter Code Golf sessions? Well, I guess almost anything. The Challenge The shortest code by character count to display a nice ASCII Spiral made of asterisks ('*'). Input is a single number, R, that will be the x-size of the Spiral. The other dimension (y) is always R-2. The program can assume R to be always odd and = 5. Some examples: Input 7 Output ******* * * * *** * * * * ***** * Input 9 Output ********* * * * ***** * * * * * * *** * * * * * ******* * Input 11 Output *********** * * * ******* * * * * * * * *** * * * * * * * * ***** * * * * * ********* * Code count includes input/output (i.e., full program). Any language is permitted. My easily beatable 303 chars long Python example: import sys; d=int(sys.argv[1]); a=[d*[' '] for i in range(d-2)]; r=[0,-1,0,1]; x=d-1;y=x-2;z=0;pz=d-2;v=2; while d>2: while v>0: while pz>0: a[y][x]='*'; pz-=1; if pz>0: x+=r[z]; y+=r[(z+1)%4]; z=(z+1)%4; pz=d; v-=1; v=2;d-=2;pz=d; for w in a: print ''.join(w); Now, enter the Spiral...

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• Design to distribute work when generating task oriented input for legacy dos application?

  - by TheDeeno

  I'm attempting to automate a really old dos application. I've decided the best way to do this is via input redirection. The legacy app (menu driven) has many tasks within tasks with branching logic. In order to easily understand and reuse the input for these tasks, I'd like to break them into bit size pieces. Since I'll need to start a fresh app on each run, repeating a context to consume a bit might be messy. I'd like to create an object model that: allows me to concentrate on the task at hand allows me to reuse common tasks from different start points prevents me from calling a task from the wrong start point To be more explicit, given I have the following task hierarchy: START A A1 A1a A1b A2 A2a B B1 B1a I'd like an object model that lets me generate an input file for task "A1b" buy using building blocks like: START -> do_A, do_A1, do_A1b but prevents me from: START -> do_A1 // because I'm assuming a different call chain from above This will help me write "do_A1b" because I can always assume the same starting context and will simplify writing "do_A1a" because it has THE SAME starting context. What patterns will help me out here? I'm using ruby at the moment so if dynamic language features can help, I'm game.

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• Design pattern to use instead of multiple inheritance

  - by mizipzor

  Coming from a C++ background, Im used to multiple inheritance. I like the feeling of a shotgun squarely aimed at my foot. Nowadays, I work more in C# and Java, where you can only inherit one baseclass but implement any number of interfaces (did I get the terminology right?). For example, lets consider two classes that implement a common interface but different (yet required) baseclasses: public class TypeA : CustomButtonUserControl, IMagician { public void DoMagic() { // ... } } public class TypeB : CustomTextUserControl, IMagician { public void DoMagic() { // ... } } Both classes are UserControls so I cant substitute the base class. Both needs to implement the DoMagic function. My problem now is that both implementations of the function are identical. And I hate copy-and-paste code. The (possible) solutions: I naturally want TypeA and TypeB to share a common baseclass, where I can write that identical function definition just once. However, due to having the limit of just one baseclass, I cant find a place along the hierarchy where it fits. One could also try to implement a sort of composite pattern. Putting the DoMagic function in a separate helper class, but the function here needs (and modifies) quite a lot of internal variables/fields. Sending them all as (reference) parameters would just look bad. My gut tells me that the adapter pattern could have a place here, some class to convert between the two when necessery. But it also feels hacky. I tagged this with language-agnostic since it applies to all languages that use this one-baseclass-many-interfaces approach. Also, please point out if I seem to have misunderstood any of the patterns I named. In C++ I would just make a class with the private fields, that function implementation and put it in the inheritance list. Whats the proper approach in C#/Java and the like?

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• How to test an application for correct encoding (e.g. UTF-8)

  - by Olaf

  Encoding issues are among the one topic that have bitten me most often during development. Every platform insists on its own encoding, most likely some non-UTF-8 defaults are in the game. (I'm usually working on Linux, defaulting to UTF-8, my colleagues mostly work on german Windows, defaulting to ISO-8859-1 or some similar windows codepage) I believe, that UTF-8 is a suitable standard for developing an i18nable application. However, in my experience encoding bugs are usually discovered late (even though I'm located in Germany and we have some special characters that along with ISO-8859-1 provide some detectable differences). I believe that those developers with a completely non-ASCII character set (or those that know a language that uses such a character set) are getting a head start in providing test data. But there must be a way to ease this for the rest of us as well. What [technique|tool|incentive] are people here using? How do you get your co-developers to care for these issues? How do you test for compliance? Are those tests conducted manually or automatically? Adding one possible answer upfront: I've recently discovered fliptitle.com (they are providing an easy way to get weird characters written "u?op ?pisdn" *) and I'm planning on using them to provide easily verifiable UTF-8 character strings (as most of the characters used there are at some weird binary encoding position) but there surely must be more systematic tests, patterns or techniques for ensuring UTF-8 compatibility/usage. Note: Even though there's an accepted answer, I'd like to know of more techniques and patterns if there are some. Please add more answers if you have more ideas. And it has not been easy choosing only one answer for acceptance. I've chosen the regexp answer for the least expected angle to tackle the problem although there would be reasons to choose other answers as well. Too bad only one answer can be accepted. Thank you for your input. *) that's "upside down" written "upside down" for those that cannot see those characters due to font problems

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• Algorithm to find the percentage of how much two texts are identical

  - by qster

  What algorithm would you suggest to identify how much from 0 to 1 (float) two texts are identical? Note that I don't mean similar (ie, they say the same thing but in a different way), I mean exact same words, but one of the two texts could have extra words or words slightly different or extra new lines and stuff like that. A good example of the algorithm I want is the one google uses to identify duplicate content in websites (X search results very similar to the ones shown have been omitted, click here to see them). The reason I need it is because my website has the ability for users to post comments; similar but different pages currently have their own comments, so many users ended up copy&pasting their comments on all the similar pages. Now I want to merge them (all similar pages will "share" the comments, and if you post it on page A it will appear on similar page B), and I would like to programatically erase all those copy&pasted comments from the same user. I have quite a few million comments but speed shouldn't be an issue since this is a one time thing that will run in the background. The programming language doesn't really matter (as long as it can interface to a MySQL database), but I was thinking of doing it in C++.

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• Which languages support *recursive* function literals / anonymous functions?

  - by Hugh Allen

  It seems quite a few mainstream languages support function literals these days. They are also called anonymous functions, but I don't care if they have a name. The important thing is that a function literal is an expression which yields a function which hasn't already been defined elsewhere, so for example in C, &printf doesn't count. EDIT to add: if you have a genuine function literal expression <exp>, you should be able to pass it to a function f(<exp>) or immediately apply it to an argument, ie. <exp>(5). I'm curious which languages let you write function literals which are recursive. Wikipedia's "anonymous recursion" article doesn't give any programming examples. Let's use the recursive factorial function as the example. Here are the ones I know: JavaScript / ECMAScript can do it with callee: function(n){if (n<2) {return 1;} else {return n * arguments.callee(n-1);}} it's easy in languages with letrec, eg Haskell (which calls it let): let fac x = if x<2 then 1 else fac (x-1) * x in fac and there are equivalents in Lisp and Scheme. Note that the binding of fac is local to the expression, so the whole expression is in fact an anonymous function. Are there any others?

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• Linear feedback shift register?

  - by Mattia Gobbi

  Lately I bumped repeatedly into the concept of LFSR, that I find quite interesting because of its links with different fields and also fascinating in itself. It took me some effort to understand, the final help was this really good page, much better than the (at first) cryptic wikipedia entry. So I wanted to write some small code for a program that worked like a LFSR. To be more precise, that somehow showed how a LFSR works. Here's the cleanest thing I could come up with after some lenghtier attempts (Python): def lfsr(seed, taps): sr, xor = seed, 0 while 1: for t in taps: xor += int(sr[t-1]) if xor%2 == 0.0: xor = 0 else: xor = 1 print xor sr, xor = str(xor) + sr[:-1], 0 print sr if sr == seed: break lfsr('11001001', (8,7,6,1)) #example I named "xor" the output of the XOR function, not very correct. However, this is just meant to show how it circles through its possible states, in fact you noticed the register is represented by a string. Not much logical coherence. This can be easily turned into a nice toy you can watch for hours (at least I could :-) def lfsr(seed, taps): import time sr, xor = seed, 0 while 1: for t in taps: xor += int(sr[t-1]) if xor%2 == 0.0: xor = 0 else: xor = 1 print xor print time.sleep(0.75) sr, xor = str(xor) + sr[:-1], 0 print sr print time.sleep(0.75) Then it struck me, what use is this in writing software? I heard it can generate random numbers; is it true? how? So, it would be nice if someone could: explain how to use such a device in software development come up with some code, to support the point above or just like mine to show different ways to do it, in any language Also, as theres not much didactic stuff around about this piece of logic and digital circuitry, it would be nice if this could be a place for noobies (like me) to get a better understanding of this thing, or better, to understand what it is and how it can be useful when writing software. Should have made it a community wiki? That said, if someone feels like golfing... you're welcome.

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• Method of transforming 3D vectors with a matrix

  - by Drew Noakes

  I've been doing some reading on transforming Vector3 with matrices, and am tossing up digging deeper into the math and coding this myself versus using existing code. For whatever reason my school curriculum never included matrices, so I'm filling a gap in my knowledge. Thankfully I only need a few simple things, I think. Context is that I'm programming a robot for the RoboCup 3D league. I'm coding it in C# but it'll have to run on Mono. Ideally I wouldn't use any existing graphics libraries for this (WinForms/WPF/XNA) as all I really need is a neat subset of matrix transformations. Specifically, I need translation and x/y/z rotations, and a way of combining multiple transformations into a single matrix. This will then be applied to my own Vector3 type to produce the transformed Vector3. I've read different advice about this. For example, some model the transformation with a 4x3 matrix, others with a 4x4 matrix. Also, some examples show that you need a forth value for the vector's matrix of 1. What happens to this value when it's included in the output? [1 0 0 0] [x y z 1] * [0 1 0 0] = [a b c d] [0 0 1 0] [2 4 6 1] The parts I'm missing are: What sizes my matrices should be Compositing transformations by multiplying the transformation matrices together Transforming 3D vectors with the resulting matrix As I mostly just want to get this running, any psuedo-code would be great. Information about what matrix values perform what transformations is quite clearly defined on many pages, so need not be discussed here unless you're very keen :)

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• Automatic testing of GUI related private methods

  - by Stein G. Strindhaug

  When it comes to GUI programming (at least for web) I feel that often the only thing that would be useful to unit test is some of the private methods*. While unit testing makes perfect sense for back-end code, I feel it doesn't quite fit the GUI classes. What is the best way to add automatic testing of these? * Why I think the only methods useful to test is private: Often when I write GUI classes they don't even have any public methods except for the constructor. The public methods if any is trivial, and the constructor does most of the job calling private methods. They receive some data from server does a lot of trivial output and feeds data to the constructor of other classes contained inside it, adding listeners that calls a (more or less directly) calls the server... Most of it pretty trivial (the hardest part is the layout: css, IE, etc.) but sometimes I create some private method that does some advanced tricks, which I definitely do not want to be publicly visible (because it's closely coupled to the implementation of the layout, and likely to change), but is sufficiently complicated to break. These are often only called by the constructor or repeatedly by events in the code, not by any public methods at all. I'd like to have a way to test this type of methods, without making it public or resorting to reflection trickery. (BTW: I'm currently using GWT, but I feel this applies to most languages/frameworks I've used when coding for GUI)

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